The present invention concerns a spark plug of an internal combustion engine, in particular for use in Otto-cycle gas engines, comprising an insulator body, at least one fixed ground electrode carrier arrangement and at least one fixed central electrode carrier, wherein a spark plug housing having at least two parts encloses the insulator body.
The spark plugs available at the present time for industrial gas engines are in many cases products which were derived from the automobile industry and adapted by suitable improvements for the preferential use in industrial gas engines. Those spark plugs generally have a fixed cylindrical central electrode provided with a precious metal pin. In the case of the fixed ground electrodes, both a hook electrode and also between two and four laterally disposed electrode fingers are used. Such ground electrodes can also be provided with a precious metal plate portion. Spark plugs of that kind are known from EP 0 834 973 A2, EP 0 859 436 A1, EP 1 049 222 A1, DE 196 41 856 A1 and WO 95/25372. Spark plugs of the general kind set forth, with multi-part spark plug housings, are known for example from GB 156 087 A or U.S. Pat. No. 6,152,095 A. A major disadvantage of the spark plugs known from the state of the art is that their resistance to pressure is not sufficiently good for on-going operation. It thus frequently happens in the case of spark plugs in accordance with the state of the art that the insulator body or the base central electrode is unintentionally expelled. If this happens under operating conditions in which a high internal pressure obtains in the cylinder of the internal combustion engine, that can involve explosive expulsion of the insulator body and/or the base central electrode in the case of spark plugs in accordance with the state of the art, which inter alia can also represent a danger to operating personnel present.